Concrete Slab Calculator
Estimate slab concrete in cubic yards with thickness and waste settings.
Open ToolIndustry-accurate CMU block, mortar, and cost estimates for walls, foundations, and any construction project.
Prices vary by region & supplier. Override with your local quotes for a more accurate estimate.
Get accurate block estimates in three simple steps
Input your wall length, height, and choose your preferred unit of measurement. Add any door or window openings.
Select block size, adjust mortar joint thickness, and set your waste factor percentage for accurate planning.
Instantly see total blocks needed, mortar bags required, estimated costs, and a visual wall preview.
Choose the right CMU block for your project
The most common concrete masonry unit. Ideal for load-bearing walls, foundations, and general construction projects.
Used at corners and ends of walls for proper running bond pattern. Essential for professional masonry work.
Solid block used to cap the top of walls. Provides a smooth, finished surface and prevents debris from entering cores.
Wider block providing extra insulation and structural integrity. Used in commercial and industrial applications.
Use specialized calculators for slab volume, sonotube piers, concrete bag count, footing concrete, mix ratio, and retaining wall planning.
Estimate slab concrete in cubic yards with thickness and waste settings.
Open ToolConvert pour size into 40 lb, 60 lb, and 80 lb bag quantities.
Open ToolCalculate concrete for round tube forms, piers, and post holes.
Open ToolEverything you need to know about concrete block calculations
For standard 8x8x16 inch CMU blocks with 3/8-inch mortar joints, you need approximately 1.125 blocks per square foot of wall area. This accounts for mortar joint spacing between blocks.
As a general rule, one 80-pound bag of mortar mix will lay approximately 12 to 14 standard concrete blocks with 3/8-inch joints.
A waste factor of 5% to 10% is recommended for most projects. Complex walls with many cuts may need 10% to 15%.
The industry standard mortar joint thickness is 3/8 inch (0.375 in).
Measure each opening and subtract combined opening area from total wall area. Then calculate on the net wall area.
These tools use standard estimating formulas with adjustable assumptions. Always verify with local requirements and professionals for critical work.
Use our free calculator above to get accurate block and mortar estimates in seconds.
Start Calculating